优化：重构代码

jodconverter-web/src/main/java/cn/keking/service/impl/MediaFilePreviewImpl.java

@@ -2,8 +2,6 @@ package cn.keking.service.impl;
 
 import cn.keking.model.FileAttribute;
 import cn.keking.service.FilePreview;
-import cn.keking.utils.FileUtils;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 import org.springframework.ui.Model;
 /**
@@ -15,9 +13,6 @@ import org.springframework.ui.Model;
 @Service
 public class MediaFilePreviewImpl implements FilePreview {
 
-    @Autowired
-    FileUtils fileUtils;
-
     @Override
     public String filePreviewHandle(String url, Model model, FileAttribute fileAttribute) {
         model.addAttribute("mediaUrl", url);